Traditional industrial radiographic inspections have for many years utilized Image Quality Indicators (IQIs), which can be hole and/or wire type, to validate radiographic techniques and inspections. Radiographic film techniques and inspections have required that plaques of given materials and thicknesses with specified hole diameters and/or wires with specified diameters to be appropriately placed on the part to be inspected and that the required plaque hole and/or wire be clearly visible in the resulting radiograph. The proper application of these IQIs has been commonly accepted as validation for a given radiographic film technique and inspection.
Newer digital radiographic inspection techniques (i.e. digital and computed radiography and computed tomography) present several issues with respect to the application of these traditional plaque and wire type IQIs. In the case of digital radiography (DR) and computed radiography (CR), their characteristic responses for spatial resolution and contrast to noise ratio (CNR) are significantly different than film. Traditional IQIs may not be sufficient to validate a DR or CR technique or inspection. Representative Quality Indications (RQIs) are used when traditional IQIs are not adequate. For computed tomography (CT), the three-dimensional scanning and imaging capability tend to invalidate any IQI placed on the exterior of a part. For CT technique validation, RQIs are commonly required (ASTM E1570 Standard Practice for Computed Tomographic (CT) Examination).
RQIs are defined in ASTM E1817, Standard Practice for Controlling Quality of Radiological Examination by Using Representative Quality Indicators (RQIs). The RQI is an object that is representative of the part being inspected. It also contains known indications that are representative of the inspection criteria/defective conditions. It can be a fabricated or an actual production part. In either case, the RQI shall be characterized and the dimensional measurements of anomalous indicators confirmed. It is common to refer to RQIs used for CT as Phantoms.
For many of the industrial CT applications, the cost to design, build, and characterize an appropriate RQI can be extremely high. In programs with limited production runs and/or very costly items, this cost cannot be supported. In some cases, it may not even be possible to build and characterize the RQI no matter what the cost. As a result, CT inspections are being performed without validating either the capability of the inspection technique or sensitivity of a given inspection.
The objective of the present invention is to address the aforementioned issue. In particular, the present invention introduces a CT technique that utilizes an additional manipulator with the IQIs. By utilizing the present invention, internal conditions of a test object can be simulated.